JP7208985B2 - Passive damping system for mass flow controllers - Google Patents

Description

[Cross reference to related applications]
This application claims priority to U.S. Provisional Patent Application No. 62/568,152, filed October 4, 2017, entitled "PASSIVE DAMPING SYSTEM FOR MASS FLOW CONTROLLER." The entire contents of which are hereby incorporated by reference for all purposes.

TECHNICAL FIELD This disclosure relates generally to nonlinear artifacts that occur during operation of mass flow controllers, and more particularly to passive damping systems that efficiently and effectively dampen nonlinear artifacts that occur during operation of mass flow controllers. .

The subject matter disclosed herein relates generally to mass flow controller systems and operations, and more particularly to passively dampening vibrations experienced by mass flow controllers.

Many industrial processes require precise control of various process fluids. For example, in the semiconductor industry, mass flow meters (MFM) are used to precisely measure the amount of process fluid introduced into a process chamber. In addition to measuring mass flow rate, a mass flow controller (MFC) is used to precisely measure and control the amount of process fluid introduced into the process chamber. It should be understood that the term fluid, as used herein, applies to any type of gas, liquid, or vapor for which control of flow rate may be important.

Flow rates for a single MFC can vary from a few cubic centimeters per minute to hundreds of liters per minute, pressure conditions can range from sub-atmospheric to 100 PSIA, and gases range from helium to relatively heavy It can range from sulfur hexafluoride. Such broad control conditions can result in flow dynamics in the MFC's valve cavity causing oscillations over a broad frequency range (eg, 400 Hz to 1000 Hz). At one or more of these frequencies, the MFC can experience universal resonant vibrations as fluid flows through the MFC's control valves. This oscillation caused by fluid flow dynamics is transmitted throughout the MFC as the flow excitation approaches the natural frequency of the MFC system. Such vibrations applied to the MFC can limit the accuracy of the MFC's controlled flow rate.

The present disclosure describes a passive damping system that interacts with a portion of a mass flow controller and is configured to attenuate non-linear artifacts introduced during operation of valves of the controller.

In one aspect, the present disclosure is a mass flow controller comprising an inlet configured to receive a fluid, a flow path for said fluid through said mass flow controller, and a flow path through said flow path. a mass flow sensor configured to provide a signal corresponding to the mass flow rate of said fluid; a control valve configured to control flow of said fluid out of an outlet of said mass flow controller; and said control valve. and a passive damping system configured to dissipate vibrations caused by fluid flow induced in the mass flow controller.

In some embodiments, the mass flow controller further comprises a valve base having a recess. In these embodiments, the passive damping system further comprises a damping pad between the housing portion of the valve base and the diaphragm lining of the control valve. In some particular embodiments, the passive damping system further comprises a damping washer. In some particular embodiments, the passive damping system further comprises one or more plunger balls between the damping pad and the valve base. In some particular embodiments, the plunger ball is spring-biased. In some particular embodiments, the plunger ball is made from stainless steel or other metal. In some particular embodiments, the passive damping system further comprises a wave spring between the damping pad and the valve base.

In another aspect, the present disclosure is a mass flow controller comprising an inlet configured to receive a fluid, a flow path for said fluid through said mass flow controller, and a flow path through said flow path. a mass flow sensor configured to provide a signal corresponding to the mass flow rate of said fluid; a control valve configured to control the flow of said fluid out of an outlet of said mass flow controller; A mass flow controller comprising a housing and a damping pad between said control valve. In some embodiments, the dampening pad is between a containment portion of the stationary body and a backing plate of the control valve. Further, a washer between said damping pad and said fixed body. In some particular embodiments, a spring device between said washer and said fixing body. In some particular embodiments, the damping pad extends from the control valve approximately to the stationary body.

In a further aspect, the present disclosure provides a mass flow controller comprising an inlet configured to receive a fluid, a flow path for said fluid as it passes through said mass flow controller, and a mass flow sensor configured to provide a signal corresponding to the mass flow rate of said fluid therethrough; and a control valve assembly configured to control the flow of said fluid out of an outlet of said mass flow controller; It relates to a mass flow controller comprising a valve base housing and a spring device between said control valve. In some particular embodiments, the spring device is between the recessed portion of the valve base and a diaphragm liner. In some particular embodiments, said spring device comprises one or more plunger balls. In some particular embodiments, said spring device comprises one or more wave springs. In some particular embodiments, a washer between said spring device and diaphragm backing. In some particular embodiments, a dampening pad between said spring device and diaphragm backing.

Further embodiments, advantages and novel features are described in the detailed description.

Exemplary embodiments of the disclosed subject matter are described in detail below with reference to the accompanying drawings. The accompanying drawings are incorporated herein by reference.

[0014] Fig. 3 illustrates a mass flow controller with a passive damping system in accordance with one disclosed embodiment; 2 illustrates a plunger ball embodiment of the passive damping system of FIG. 1 in accordance with one disclosed embodiment; FIG. 2 illustrates a spring-biased embodiment of the passive damping system of FIG. 1 in accordance with one disclosed embodiment; FIG. 2 illustrates a soft washer embodiment of the passive damping system of FIG. 1 according to one embodiment; FIG.

The disclosed embodiments comprise a system for improving mass flow controller accuracy by reducing vibrations induced by fluid flow dynamics in the control valves of the mass flow controller. The disclosed embodiments and their advantages are best understood with reference to FIGS. 1-4 of the drawings. The disclosed embodiments may not be limited to any particular type of mass flow sensing technology. The mass flow sensing techniques may include thermal-based methods using thermal sensors, pressure-based methods using pressure sensors and flow restrictors to calculate flow, and Coriolis-based sensing methods. Other features and advantages of the disclosed embodiments will become apparent to one of ordinary skill in the art upon examination of the accompanying drawings and following detailed description. All such additional features and advantages are intended to be included within the scope of the disclosed embodiments. Additionally, the depicted diagrams are exemplary only and are not intended to assert or imply any limitation as to the environment, architecture, design, or processes in which different embodiments may be implemented.

Although FIG. 1 illustrates an example thermal mass flow controller (MFC) 100 according to the disclosed embodiments, other types of mass flow sensing methods can be included. Mass flow controller 100 comprises block 110, which is the platform on which the components of MFC 100 are mounted. A thermal mass flow meter 140 and a valve assembly 150 including a control valve 170 are mounted on block 110 between fluid inlet 120 and fluid outlet 130 . A thermal mass flow meter 140 typically includes a bypass 142 through which a majority of the fluid flows, and a thermal flow sensor 146 through which a lesser portion of the fluid flows. Bypass 142 is conditioned with a known fluid to determine the appropriate relationship between the fluid flowing through the mass flow sensor and the fluid flowing through bypass 142 at various known flow rates, thereby producing a thermal flow sensor output signal , the total flow rate through the flow meter can be determined. Thermal flow sensor 146 and bypass 142 can then be connected to control valve 170 and control electronics 160 and then again regulated under known conditions. The response of the control electronics 160 and control valve 170 is then such that the overall response of the system to changes in setpoint or input pressure is known and used to control the system to provide the desired response. characterized as can be.

Thermal flow sensor 146 is housed within sensor housing 102 (portion shown removed to show thermal flow sensor 146) mounted to mounting plate 108. FIG. Thermal flow sensor 146 is a small diameter tube, commonly referred to as a capillary tube, having a sensor inlet section 146A, a sensor outlet section 146B, and a sensor measuring section around which two resistive coils or windings 147, 148 are arranged. 146C. In operation, current is applied to the two resistive windings 147, 148 which are in thermal contact with the sensor measuring portion 146C. The current in resistance windings 147 , 148 heats the fluid flowing through measuring portion 146 C to a temperature above the temperature of the fluid flowing through bypass 142 . The resistance of windings 147, 148 varies with temperature. As fluid flows through the sensor conduit, heat is transferred from upstream resistor 147 to downstream resistor 148, with a temperature difference proportional to mass flow through the sensor.

From the two resistive windings 147, 148 an electrical signal related to the flow rate through the sensor is derived. The electrical signal can be derived in a number of different ways, such as from differences in the resistance of the resistor windings, or from differences in the amount of energy provided to each resistor winding to maintain each winding at a particular temperature. . For examples of various ways in which an electrical signal correlated with fluid flow rate in a thermal mass flow meter may be determined, see, for example, commonly owned U.S. Pat. 6,845,659. The electrical signals derived from the resistive windings 147, 148 after signal processing comprise sensor output signals.

The sensor output signal can be correlated with mass flow rate in the mass flow meter to determine fluid flow rate when the electrical signal is measured. By correlating the sensor output signal, typically first with the flow rate at sensor 146 and then with the mass flow rate at bypass 142, the total flow rate through the flow meter can be determined and control valve 170 controlled accordingly. be able to. The correlation between sensor output signal and fluid flow rate is complex and depends on many operating conditions, including fluid species, flow rate, inlet and/or outlet pressure, temperature, and the like.

The process of correlating raw sensor output to fluid flow requires adjustment and/or calibration of the mass flow controller. For example, a mass flow sensor can be tuned by passing a known volume of a known fluid through the sensor portion and adjusting some specific signal processing parameters to provide a response that accurately represents the fluid flow rate. . For example, the output can be normalized such that a specified voltage range, such as 0 V to 5 V for the sensor output, corresponds to a flow rate range from zero to the top of the range for the sensor. The output can also be linear so that changes in sensor output correspond linearly to changes in flow rate. For example, if the output is linearized, doubling the fluid output will double the electrical output. The dynamic response of the sensor, ie the inaccurate effects of pressure or flow changes that occur when the flow or pressure changes are determined, can be determined so that these effects can be compensated for.

If the type of fluid used by the end-user is different from the type of fluid used for adjustment and/or calibration, or if the operating conditions used by the end-user, such as inlet and outlet pressures, temperatures, flow ranges, etc. , adjustment and/or calibration, the operation of the mass flow controller is generally degraded. For this reason, the flowmeter can be adjusted or calibrated with additional fluids (referred to as "surrogate fluids") and/or operating conditions, and any changes necessary to provide sufficient response are reflected in the look. stored in the up table. Wang et al., U.S. Pat. No. 7,272,512, entitled "Flow Sensor Signal Conversion," owned by the assignee of the present invention and incorporated herein by reference, describes each different process used. Rather than requiring a substitute fluid to calibrate the device to the fluid, a system is described that uses the properties of different gases to tune the response.

In addition, the mass flow controller 100 can include a pressure transducer 112 coupled to the flow path, typically but not exclusively, somewhere upstream of the bypass 142 to measure pressure within the flow path. . Pressure transducer 112 provides a pressure signal indicative of pressure. According to the disclosed embodiment, pressure transducer 112 is used to measure pressure during flow measurement.

Control electronics 160 controls the position of control valve 170 in accordance with a set point indicative of the desired mass flow rate and an electrical flow signal from the mass flow sensor indicative of the actual mass flow rate of fluid flowing through the sensor conduit. And conventional feedback control such as proportional control, integral control, proportional-integral (PI) control, derivative control, proportional-derivative (PD) control, integral-derivative (ID) control and proportional-integral-derivative (PID) control A method is used to control the flow rate of a fluid in a mass flow controller. A control signal (e.g., control valve drive signal) is generated based on an error signal, which is the difference between a setpoint signal indicative of the desired mass flow rate of the fluid and a feedback signal related to the actual mass flow rate sensed by the mass flow sensor. generated. A control valve is positioned within the main fluid flow path (usually downstream of the bypass and mass flow sensor) and is regulated (eg, opened and closed) to vary the mass flow rate of fluid flowing through the main fluid flow path. and this control is provided by mass flow controller 100 .

In the illustrated example, the flow rate is provided as a voltage signal by conductor 158 to closed loop system controller 160 . The signal is amplified, processed, and supplied to control valve assembly 150 using conductor 159 to alter the flow rate. To this end, controller 160 compares the signal from mass flow sensor 140 to a predetermined value and adjusts proportional valve 170 accordingly to achieve the desired flow rate.

Control valve 170 may be a piezo or other technology valve configured to operate at flow rates of 2 standard liters per minute or greater. A passive damping system 180 may be implemented in the control valve 170 of the mass flow controller 100 to avoid inaccuracies caused by vibrations induced by fluid flow dynamics in the control valve 170 of the mass flow controller 100 . Passive damping system 180 (an embodiment of which is described in detail below with reference to FIGS. 2-4) is designed to reduce flow-induced vibrations caused by the operation of control valve 170 to other parts of mass flow controller 100. provide a mechanism that reduces or eliminates transmission to the Passive damping system 180 dissipates vibrational energy before it is transferred to other parts of mass flow controller 100 . Multiple configurations of passive damping system 180 are envisioned. For example, the passive damping system 180 may place one or more spring-biased plunger balls around the control valve 170 to dissipate vibrations generated by fluid flow through the mass flow controller 100; Placement of a spring around 170 and/or placement of a high damping soft washer around control valve 170 may be included. As used herein, the term passive means that the system is entirely mechanical with no electrical controls.

FIG. 2 illustrates a plunger ball embodiment 180A of a passive damping system 180 according to one embodiment of the disclosure. Plunger ball embodiment 180A includes one or more spring-biased plungers 200 . Spring-loaded plunger 200 includes plunger housing 202 . A spring 204 is disposed within plunger housing 202 and exerts a force on plunger ball 208 in direction 220 . Plunger ball 208 abuts washer 210 positioned adjacent damping pad 212 . As vibrations occur in control valve assembly 150 , the spring force exerted by spring 204 on plunger ball 208 is transferred to washer 210 and damping pad 212 . The spring force is sufficient to hold damping pad 212 in position such that the vibrational energy generated in control valve assembly 150 is dissipated by deformation of damping pad 212 . When the control valve 170 is opened (eg, when the control valve 170 moves in direction 206), the spring force produced by the spring-biased plunger 200 is offset by the lifting force of the actuator of the control valve 170, causing the control valve The 170 actuator has minimal impact on the lift stroke.

Generally, the spring-biased plunger 200 can be placed between any source of vibration and a fixed mounting element of the mass flow controller 100 . For example, the spring-biased plunger 200 can be located between the diaphragm backing 222 and the valve base 230 of the mass flow controller 100 . Diaphragm 226 underlies diaphragm backing 222 and over control valve 170 . Fluid flow can cause vibration of diaphragm 226 and the stem of control valve 170 , which can cause vibration of diaphragm backing 222 . In this particular embodiment, the plunger ball embodiment 180A is installed within the recessed portion 228A of the valve base 230. As shown in FIG. The recessed portion 228A can be obtained by milling a portion of the valve base 230. As shown in FIG. In this particular embodiment, damping pad 212 interacts with diaphragm backing 222 and spring-loaded plunger 200 is secured to valve base 230 . In either case, washer 210 may be located between damping pad 212 and spring-loaded plunger 200 . Once the vibrational energy is dissipated from the diaphragm backing 222 into the passive damping system 180, the total vibration of the control valve 170 is significantly reduced and excitation of resonant modes throughout the mass flow controller 100 is avoided.

Spring-loaded plunger 200 and washer 210 may be made from stainless steel or other material. Damping pad 212 may be made from polyurethane rubber or other resilient material. Plunger ball embodiment 180A includes one or more spring-biased plungers 200 . In one embodiment, the plunger ball embodiment 180A comprises three to six or more spring-biased plungers 200. FIG.

FIG. 3 illustrates a spring-biased embodiment 180B of the passive damping system 180 according to one disclosed embodiment. Spring-biased embodiment 180B includes one or more springs 300 . Spring 300 may be a wave spring. A wave spring, as used herein, is a spring made from flat wire that has waves added to it to give it a spring action. Wave springs can also be made from other wire shapes (eg, cylindrical, rectangular, etc.). In other embodiments, spring 300 can be a coil spring with a dampening coating. The dampening coating can act as a damper to dissipate vibrational energy from control valve 170 . Spring 300 exerts a force on washer 310 in direction 320 . Washer 310 is located adjacent damping pad 312 . When vibration occurs in control valve 170 , the spring force provided by spring 300 exerts force on washer 310 and damping pad 312 . The spring force is sufficient to hold the damping pad 312 in position so that the vibrational energy is dissipated by deformation of the damping pad 312 . When control valve 170 is opened (eg, when control valve 170 moves in direction 306), the spring force produced by spring 300 is offset by the lifting force of the actuator of control valve 170, causing the actuator of control valve 170 to rise. has minimal effect on the up stroke.

Generally, spring 300 can be placed between any source of vibration and a fixed mounting element of mass flow controller 100 . For example, spring 300 may be located between diaphragm backing 222 and valve base 230 of mass flow controller 100 . In this particular embodiment, spring biased embodiment 180B is installed within recessed portion 228B of valve base 230 . Recessed portion 228B may be obtained by milling a portion of valve base 230 . When control valve 170 is opened (eg, moved in direction 306 ), spring 300 can abut valve base 230 to provide a fixed frame for spring 300 . Once the vibrational energy is dissipated from the diaphragm backing 222 into the passive damping system 180B, the total vibration of the control valve 170 is significantly reduced and excitation of resonant modes throughout the mass flow controller 100 is avoided.

Spring 300 and washer 310 may be made from stainless steel or other material. Damping pad 312 may be made from polyurethane rubber or other resilient material. Spring-biased embodiment 180B includes one or more springs 300 . In the illustrated embodiment, the spring-biased embodiment 180B comprises a single spring 300 positioned around the control valve 170 .

FIG. 4 illustrates a soft washer embodiment 180C of passive damping system 180 according to one embodiment. Soft washer embodiment 180C comprises soft washer 400 . Soft washer 400 may be made from polyurethane rubber or other similar elastic material. Soft washer 400 can force control valve 170 in direction 420 when control valve 170 opens by moving in direction 406 . When vibration occurs in control valve 170 , the force provided by soft washer 400 provides backside support of control valve 170 to diaphragm backing 222 . Soft washer 400 dissipates vibrational energy generated in valve assembly 150 by deformation of soft washer 400 . When control valve 170 opens (e.g., when control valve 170 moves in direction 406), the force produced by soft washer 400 in direction 420 is offset by the lifting force of the actuator of control valve 170, causing control valve 170 to It has minimal influence on the lift stroke of the actuator.

In general, soft washer 400 can be installed between any source of vibration and a fixed mounting element of mass flow controller 100 . For example, soft washer 400 can be located between diaphragm backing 222 and valve base 230 of mass flow controller 100 . In this particular embodiment, soft washer 400 is installed within recessed portion 228C of valve base 230 . When the control valve 170 is opened (eg, moved in direction 406 ), the soft washer 400 can abut the valve base 228 and provide a fixed frame for the soft washer 400 . Once the vibrational energy is dissipated from the diaphragm backing 222 into the passive damping system 180, the total vibration of the control valve 170 is significantly reduced and excitation of resonant modes throughout the mass flow controller 100 is avoided.

Soft washer 400 can be made from polyurethane rubber or other resilient material. Soft washer embodiment 180 C comprises one or more soft washers 400 . In the illustrated embodiment, soft washer embodiment 180B comprises a single soft washer 400 positioned around control valve 170 . The durometer hardness of the damping washer is based on the material's ability to dampen vibrations from the surrounding environment, and the durometer hardness can be specific to a particular mass flow controller application. The storage portion 228C can have various widths and depths depending on the requirements of a particular application. It is understood that the damping system described herein, ie, embodiments 180A-180C, can be positioned between any fixed or rigid body and the source of oscillation or vibration within the mass flow controller. should.

Although specific embodiments have been described above in detail, this description is for illustrative purposes only. Therefore, it should be understood that many of the aspects described above are not intended as essential or essential elements unless specified to the contrary. Those skilled in the art, having the benefit of this disclosure, will disclose exemplary embodiments in addition to those described above without departing from the spirit and scope of the embodiments defined in the appended claims. , and equivalent components or acts corresponding to the disclosed aspects. The scope of the appended claims should be given the broadest interpretation to encompass such variations and equivalent constructions.
[Configuration 1]
A mass flow controller,
an inlet configured to receive a fluid;
a flow path for the fluid through the mass flow controller;
a mass flow sensor configured to provide a signal corresponding to the mass flow rate of the fluid through the flow path;
a control valve configured to control the flow of said fluid out of an outlet of said mass flow controller;
a passive damping system configured to dissipate vibrations caused by fluid flow provided by the control valve;
a mass flow controller.
[Configuration 2]
2. The mass flow controller of arrangement 1, further comprising a valve base having a recess.
[Configuration 3]
3. The mass flow controller of configuration 2, wherein the passive damping system further comprises a damping pad between the housing portion of the valve base and a diaphragm backing of the control valve.
[Configuration 4]
4. The mass flow controller of configuration 3, wherein the passive damping system further comprises a damping washer.
[Configuration 5]
4. The mass flow controller of configuration 3, wherein the passive damping system further comprises one or more plunger balls between the damping pad and the valve base.
[Configuration 6]
6. The mass flow controller of configuration 5, wherein the one or more plunger balls are coupled to the valve base.
[Configuration 7]
6. The mass flow controller of configuration 5, wherein the plunger ball is spring biased.
[Configuration 8]
7. The mass flow controller of configuration 6, wherein the plunger ball is made from stainless steel or other metal or alloy.
[Configuration 9]
4. The mass flow controller of configuration 3, wherein the passive damping system further comprises a wave spring between the damping pad and the valve base.
[Configuration 10]
A mass flow controller,
an inlet configured to receive a fluid;
a flow path for the fluid through the mass flow controller;
a mass flow sensor configured to provide a signal corresponding to the mass flow rate of the fluid through the flow path;
a control valve configured to control the flow of said fluid out of an outlet of said mass flow controller;
a damping pad between the housing portion of the stationary body and the control valve;
a mass flow controller.
[Configuration 11]
11. The mass flow controller of configuration 10, wherein the damping pad is between a housing portion of the fixed body and a backing plate of the control valve.
[Configuration 12]
11. The mass flow controller of configuration 10, further comprising a washer between said damping pad and said stationary body.
[Configuration 13]
13. The mass flow controller of configuration 12, further comprising a spring device between said washer and said stationary body.
[Configuration 14]
11. The mass flow controller of configuration 10, wherein the dampening pad extends from the control valve to approximately the fixed body.
[Configuration 15]
A mass flow controller,
an inlet configured to receive a fluid;
a flow path for the fluid through the mass flow controller;
a mass flow sensor configured to provide a signal corresponding to the mass flow rate of the fluid through the flow path;
a control valve configured to control the flow of said fluid out of an outlet of said mass flow controller;
a spring device between the housing of the valve base and the control valve;
a mass flow controller.
[Configuration 16]
16. The mass flow controller of configuration 15, wherein the spring device is between the recessed portion of the valve base and a diaphragm backing.
[Configuration 17]
16. The mass flow controller of configuration 15, wherein the spring device comprises one or more plunger balls.
[Configuration 18]
16. The mass flow controller of configuration 15, wherein the spring device comprises one or more wave springs.
[Configuration 19]
16. The mass flow controller of configuration 15, further comprising a washer between the spring device and diaphragm backing.
[Configuration 20]
16. The mass flow controller of configuration 15, further comprising a dampening pad between the spring device and diaphragm backing.
[Configuration 21]
Mass flow sensor technologies include thermal sensors used in thermal mass flow controllers, pressure mass flow controllers that calculate flow using pressure sensors and flow restrictors, and Coriolis flow controllers that use Coriolis tubes for flow sensing. The mass flow controller of arrangement 1, comprising: a mass flow controller of the formula:

Claims (19)

A mass flow controller,
an inlet configured to receive a fluid;
a flow path for the fluid through the mass flow controller;
a mass flow sensor configured to provide a signal corresponding to the mass flow rate of the fluid through the flow path;
a control valve configured to control the flow of said fluid out of an outlet of said mass flow controller;
a passive damping system configured to dissipate vibrations caused by fluid flow provided by the control valve ;
a valve base having a housing portion;
with
The passive damping system further comprises a damping pad between the recessed portion of the valve base and a diaphragm lining of the control valve.
Mass flow controller. 2. The mass flow controller of Claim 1 , wherein the passive damping system further comprises a damping washer. 2. The mass flow controller of claim 1 , wherein said passive damping system further comprises one or more plunger balls between said damping pad and said valve base. 4. The mass flow controller of Claim 3 , wherein said one or more plunger balls are coupled to said valve base. 4. The mass flow controller of claim 3 , wherein the plunger ball is spring biased. 5. The mass flow controller of Claim 4 , wherein the plunger ball is made from stainless steel or other metal or alloy. 2. The mass flow controller of claim 1 , wherein said passive damping system further comprises a wave spring between said damping pad and said valve base. A mass flow controller,
an inlet configured to receive a fluid;
a flow path for the fluid through the mass flow controller;
a mass flow sensor configured to provide a signal corresponding to the mass flow rate of the fluid through the flow path;
a control valve configured to control the flow of said fluid out of an outlet of said mass flow controller;
a damping pad between the housing portion of the stationary body and the control valve;
a mass flow controller. 9. The mass flow controller of claim 8 , wherein the damping pad is between a recessed portion of the fixed body and a backing plate of the control valve. 9. The mass flow controller of Claim 8 , further comprising a washer between said damping pad and said stationary body. 11. The mass flow controller of claim 10 , further comprising a spring device between said washer and said stationary body. 9. The mass flow controller of claim 8 , wherein said damping pad extends from said control valve to approximately said fixed body. A mass flow controller,
an inlet configured to receive a fluid;
a flow path for the fluid through the mass flow controller;
a mass flow sensor configured to provide a signal corresponding to the mass flow rate of the fluid through the flow path;
a control valve configured to control the flow of said fluid out of an outlet of said mass flow controller;
a spring device between the housing of the valve base and the control valve;
a mass flow controller. 14. The mass flow controller of claim 13, wherein the spring device is between the recessed portion of the valve base and a diaphragm backing. 14. The mass flow controller of Claim 13 , wherein the spring device comprises one or more plunger balls. 14. The mass flow controller of Claim 13 , wherein the spring device comprises one or more wave springs. 14. The mass flow controller of claim 13 , further comprising a washer between the spring device and diaphragm backing. 14. The mass flow controller of Claim 13 , further comprising a damping pad between said spring device and diaphragm backing. Mass flow sensor technologies include thermal sensors used in thermal mass flow controllers, pressure mass flow controllers that calculate flow using pressure sensors and flow restrictors, and Coriolis flow controllers that use Coriolis tubes for flow sensing. 2. The mass flow controller of claim 1, comprising a mass flow controller of the formula:

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